This invention relates to a safety cover for an electrical receptacle, and more particularly, to a combination base-plate and housing member which can be connected and capable of being locked so as to prevent access by young children or the like. The invention is designed so that an electrical plug may be plugged into the electrical receptacle while the housing member is in the locked position.
Electrical wall receptacles present much danger to young children and others who make accidential contact with such current-carrying outlets. Compounding this danger is the fact that electrical cords often suffer wear at the area where the cord meets the electrical plug. This is particularly dangerous when the receptacle or plug is exposed to water, as with an outdoor receptacle.
Safety guards designed to prevent unauthorized access to electrical receptacles do currently exist. All, however, are limited in their effectiveness or marketability due to the following reasons.
The simplest form of safety cover currently available consists of a small plastic disk with prongs extending laterally from one of its flat surfaces. This design is effective only against the smallest of children since it can be easily removed by any child physically capable of grasping and pulling an object. This category includes children as young as one year of age. This weakness is further aggravated by the action of removing and replacing these plugs as they are held in place by friction. This friction abrades the plastic prongs as they are repeatedly inserted and removed from the metal contacts within the receptacle.
More sophisticated safety devices also exist such as U.S. Pat. No. 2,526,606 which discloses a protective hood that snaps onto a special base plate. The hood engages the base plate by means of a series of interlocking flanges, each locking flange on the cover having a corresponding receiving flange on the base plate. Removal of the hood is accomplished by flexing one of its two longitudinal edges inwardly to disengage the locking flanges on the hood from those on the base plate. The patent discloses that the hood is made of sufficiently strong material so that the pressure required to release it is more than the average small child can exert. In other words, the effectiveness of this device is limiting a child's access to the receptacle and is totally dependent upon a child's ability to exert enough physical pressure on a single point on the hood. While the average small child may not be able to flex the hood inwardly with his or her hand, it will be appreciated that a small child could, by kicking or striking the hood with a toy or other implement, exert sufficient force to dislodge it from the base plate. Accordingly, protective devices which rely merely upon a child's limited strength may prove ineffective in many situations.
Another approach to the problem of protecting children from hazards associated with electrical outlets has been to cut the power to the outlet entirely when the outlet is exposed. For example, U.S. Pat. No. 2,439,708 discloses an electrical outlet with a hinged cover box having arms attached thereto which cooperate with a switch that connects the electrical lead wires to the contacts of the outlet. In operation, when the cover box is in the closed position (preventing access to the outlet), the outlet is energized. When this covering box is in its open position (unlatched and swung away from the outlet), the power to the receptacle is shut off.
While it can be appreciated that this feature of turning the power off when the outlet is exposed may be somewhat more effective than other approaches which rely solely on limiting physical access to the outlet, it is also complex and rather costly to implement. Furthermore, repeated opening and closing of the cover box subjects various component parts to wear, eventually requiring the repair or replacement of the entire receptacle. This approach is thus not subject to widespread commercial acceptance or application.
Another approach, more recently advanced, is one which seeks to limit access to an electrical outlet by means of enclosing the outlet. These covering devices consist of a base plate (which replaces the existing outlet cover plate), and either hingedly attached, or removable covers. For example, U.S. Pat. No. 4,070,078 discloses a plate mounted over the electrical outlet to expose the sockets and which has a pair of spaced apart latching elements. These latching elements are hollow and hingedly connected to the plate and are provided with spaced apart flexible abutments engagable with the latching elements for securing the closure elements against different areas of the plate to thereby enclose the sockets and electrical plugs. This approach is complex in design and although it can be seen to be somewhat effective, it still relies totally upon the supposed inability of a child to exert sufficient pressure on the two flexible abutments. In fact, however, this can be accomplished by children as young as two years of age. Another problem which can be readily seen when looking at FIG. 1 of this patent, is that an object, such as a pencil or the like, can be placed in the gap between the two hollow closure elements and used to pry the closure elements open. Also, these closure elements, due to their shape and size, and the fact that they are only held in place by the two clips at the center of the plate, could be dislodged by a small child, who either grasped and twisted, or struck one or both of the elements with a toy or other similar object. For these reasons this approach is both too costly for widespread acceptance and may not be sufficiently effective in all situations.
Still another approach to the protection of children from electrical outlets is to cover the outlet with a protective cover and base plate, which require larger hands and more dexterity to operate than are present in most small children. For example, U.S. Pat. No. 4,652,696 discloses a base plate which replaces the conventional face plate of an electrical outlet, and a cover which is attached to the base plate and is secured to the base plate by three latches which must be simultaneously released to facilitate removal of the cover. It can readily be seen that this approach is, in theory, sound and superior to previous attempts to address this safety hazard. There are, however, several problems with this design, in both of its configurations. The most obvious of these is that the structure would be extremely expensive, if not impossible, to produce, due to the limitations of existing molding and materials technology. This is due to the depth of the cover and base plate sides. Also, because of its straight sided box configuration, a small child, of no more than one year of age, could break the entire structure away from the outlet by either sitting on, climbing on or striking the cover with a foot, toy or other object, thus exposing, not only the outlet and face plate, but the bare electrical wires within the wall. Another problem is with the nature and placement of the retaining latches. These latches are thin and all of the stress exerted, when they are pushed in to disengage the cover, is concentrated in one very small area. Accordingly, with repeated usage, they would lose their elasticity and thus their effectiveness. Also, because of their placement on the sides of the cover, these latches are highly visible and vulnerable to defeat by an inquisitive child using nothing more than a pencil or even a finger.
U.S. Pat. No. 4,603,932 overcomes the problem of the vulnerability of the retaining latches to access by a child and stress concentration by providing latching projections on the edge of the cover which engage in recesses in the receiving plate, but to obtain this engagement, the cover slides with a flange on the receiving plate, which makes the cover difficult to seal against the receiving plate.
My recently granted U.S. Pat. No. 4,899,019, also provides a solution to the problem of the retaining latches by mounting them within the housing as part of an inner housing, but also has the drawback that the outer cover must slide into a flange on the receiving plate so that the device is difficult to seal.
There still exists a need, therefore, for a safety cover which effectively prevents unauthorized access to an electrical receptacle, both when there is a plug in the outlet as well as when there is not, and which can also be easily sealed to prevent water and the like from getting into it so that it can be used out of doors. This device must also be designed in such a way that it can be manufactured, using existing material and technology, in sufficient quantities and at a low enough price as to be capable of the widest possible distribution.